Borehole reveals magma’s potential in geothermal power

Ars Technica : The Icelandic Deep Drilling Project (IDDP) drills 5-km-deep boreholes to try to harness an extreme form of geothermal energy. In 2009, while drilling a 2.1-km hole, the IDDP encountered an unexpected pocket of magma where temperatures reached between 900 and 1000 °C. It was just the second time that a drill had reached magma (the first hole, in Hawaii, was sealed). Iceland’s National Power Company worked with the IDDP to study the hole and to attempt to harness the heat. The result was the first geothermal borehole that drew its heat directly from magma. Producing high-pressure steam at a record temperature of 450 °C, the hole generated 36 MW of electrical energy. While significantly less than a coal power plant, it was more than half the energy produced by a nearby traditional geothermal plant. After two years of operation a valve failed, forcing the hole to be plugged. The IDDP hopes to either fix the hole or drill a replacement nearby. And the organization continues to search for other sites where magma may be accessible for geothermal power generation.